Final answer:
The correct answer is option c. If a drug inhibits TFIID binding to the core promoter, transcription that is currently occurring would stop, but pre-initiation complexes would still form.
Step-by-step explanation:
If a drug was developed that could inhibit TFIID binding to the core promoter, it would have the following effect on transcription: Transcription that was currently occurring would stop, but pre-initiation complexes would still form.
TFIID is one of the general transcription factors that binds to the TATA box in the core promoter to recruit RNA polymerase and initiate transcription. By inhibiting TFIID binding, the drug would prevent the formation of the transcription initiation complex and halt ongoing transcription. However, the pre-initiation complexes, which consist of other transcription factors already bound to the promoter, would still form even without TFIID. These pre-initiation complexes may allow for the potential restart of transcription once the drug is removed.